Q121. Consider a "leaky" reservoir. Current volume 1,200 million gallons. Inflow 200 million gallons per month. Consumption 150 million gallons per month. Leakage 5% of current volume per month.

  1. Draw a stock and flow diagram of the situation.
  2. Draw a causal loop diagram showing the relationship between reservoir volume and the net in/out flow.
  3. Identify amount(s) and rate(s).
  4. Write the difference equation in the form $P_{n+1} = a \times P_n + b$.
  5. Calculate the expected equilibrium.
  6. Set up Excel model.
  7. Chart reservoir volume vs. time.